President Barack Obama challenged graduates at UC Irvine to fight cynicism and climate change during his commencement speech at Angel Stadium on Saturday, fueling them with the inspirational word that defined his 2008 presidential campaign and resonated with youth who helped sweep him into office.

“Cynicism is a choice,” Obama said. “Hope is a better choice.”

The nearly 30-minute address before a crowd of about 30,000 pushed ideas unveiled in his recent Climate Action Plan, which seeks to cut carbon emissions from power-producing plants by 30 percent to 2005 levels.

He also made news, announcing a $1 billion fund to help communities prepare for climate change problems.

He urged the nearly 6,700 graduates and thousands of their supporters to not feel “overwhelmed” by people who deny the existence of climate change. Obama, who drew a parallel to President John F. Kennedy’s proposal to land on the moon during a 1962 speech at Rice University, took a few political jabs at those in Congress who question the science of global warming. He pointed out that one member of Congress told him climate change is a result of “dinosaur flatulence.”

“When President Kennedy set us on a course for the moon, there were a number of people who made a serious case that it wouldn’t be worth it; it was going to be too expensive, it was going to be too hard, it would take too long. But nobody ignored the science,” Obama said. “I don’t remember anybody saying that the moon wasn’t there or that it was made of cheese.”

The challenge of climate change resonates most deeply with the generation that graduated Saturday at Angel Stadium. A Gallup Survey found that 78 percent of Americans between the ages of 18 and 29 believe climate change is real and will have an effect on the earth during their lifetimes.

Tiffany Lin, a 22-year-old who graduated with a degree in psychology, said the theme of Obama’s speech needs to be heard regularly.

“I feel the challenge of climate change is even bigger than going to the moon,” Lin said. “The moon is important, but it’s a distant place. It’s not as important as taking care of the place where we live.”

Obama’s speech Saturday was his first college commencement in California. It coincided with UCI’s 50th anniversary – an event dedicated by President Lyndon B. Johnson just one day after the Civil Rights Act passed Congress.

Obama offered a simple reason for speaking at UCI, which sent 10,000 postcard requests to the president:

“You asked.”

His speech, while heavy on climate change policy, did offer some humor, as well. Standing on a stage set up in straightaway center field, he thanked Mike Trout, the Angels’ outfielder, for “letting me cover his turf for a while”